In the activity_main.xml, we have added a FloatingActionButton, which we will use to go to NewUserActivity. To complete this task, use the following code in the onCreate() with the mentioned request code:

fab.setOnClickListener {
    val intent = Intent(this@MainActivity, NewUserActivity::class.java)
    startActivityForResult(intent, requestCode)

    /*Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
        .setAction("Action", null).show()*/
}

So, here is the complete code of MainAcivity.kt:

class MainActivity : AppCompatActivity() {

    private val requestCode: Int = 1

    private lateinit var mMainViewModel: MainViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(toolbar)

        val userListAdapter = UserListAdapter(this)
        recyclerview.adapter = userListAdapter
        recyclerview.layoutManager =  LinearLayoutManager(this)

        mMainViewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)
        mMainViewModel.getAllUsers().observe(this,
            Observer {
                    userList -> userListAdapter.setNewUser(userList!!)
            })


        fab.setOnClickListener {
            val intent = Intent(this@MainActivity, NewUserActivity::class.java)
            startActivityForResult(intent, requestCode)
        }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == this.requestCode && resultCode == Activity.RESULT_OK){
            data?.let {
            val users: Users = it.getParcelableExtra(getString(R.string.result_replay)) as Users
            mMainViewModel.insert(users)
            }
        }
    }
}

Now that we have completed the project, run the application. We will explore this in the next section.